The use of commercial sintered polycrystalline diamond compacts for the removal of materials in which the operations are conducted dry (i.e., without coolant fluid circulation over the tool) is limited because of the frictional heat generated at the rubbing interface between the diamond layer and the material being cut. If the temperatures generated by this frictional heat are permitted to become high enough, damage to the sintered diamond structure will occur and result in markedly increased cutter wear rates. Examplary tool constructions are disclosed in U.S. Pat. No. 3,745,623--Wentorf and Rocco.
Extensive experiments in which the wear of studmounted sintered polycrystalline diamond drill blanks was quantitatively measured while cutting an abrasive rock (Nugget Sandstone) under both dry and wet (water base coolant) conditions clearly illustrate the problem. Tests conducted over a speed range extending from 104-443 ft./min. demonstrated that the volume of diamond wear was independent of speed and was a linear function of the length of cut (i.e., distance cut), for both the dry and wet conditions.
It was also found that by using the water base coolant to remove the frictionally generated heat, the diamond wear rate was reduced by 93.8%.